$result=self::$PDOStatement->fetchAll(constant('PDO::FETCH_ASSOC'));
测试显示Fatal error: Uncaught Error: Call to a member function fetchAll() on null in D:\phpstudy_pro\WWW\www.test.com\PDOmysql.php:57 Stack trace: #0 D:\phpstudy_pro\WWW\www.test.com\PDOmysql.php(99): Mysql::getAll() #1 {main} thrown in D:\phpstudy_pro\WWW\www.test.com\PDOmysql.php on line 57
可是感觉代码没错误啊